Electrolytic etching apparatus



Nov. 12, 1968 She Filed Sept. 28, 1965 R 2 m MW C m o I w & T F 5 2 ,YT 0 4 5 w A 5 am 1m 7 0 0 5 0 9 4W 5 5 G 6 E Wm w a mi f M g 9 A w 0 i l 1 /T Nov. 12, 1968 A. E. GODBEHERE 3,410,782

. ELECTROLYTIC ETCHING APPARATUS Filed Sept. 28, 1965 2 Sheets-Sh eet 2 /0 m if FIG. 4 3 i? i; 37 4b 22 36 a J 4 F H 6/ 60 56 "\JVENTOR.

raiser, E Goclbehere BY WWW/9M A 7' T'GRNE Y5 United States Patent 3,410,782 ELECTROLYTIC ETCHING APPARATUS Albert E. Godbehere, Shelfield, England, assignor to Edward Pryor & Son Limited, Sheflield, England, a private limited company Filed Sept. 28, 1965, Ser. No. 490,860 5 Claims. (Cl. 204224) This invention pertains to a new and improved electrolytic etching apparatus and more particularly to an apparatus for marking metallic pieces of work with an etching process provided through electrolysis.

Electrolytic etching or electrolysis has been used for marking metallic objects for many years. The basis of this process lies in the fact that part of the surface of the piece of work goes into solution with an electrolyte when an electric current is passed from the electrolyte into the piece of work. For this process to work properly the electrolyte must be compatible with the metal in the piece of work. An example of compatible materials is an electrolyte containing sodium chloride, ammonium chloride or ammonium nitrate for use on tin plate pieces of work. In general the electric current is produced by providing an electrically conducting block connected to a power supply as the cathode and pressing this block with an absorbent material containing the electrolyte against the surface of the piece of work to be etched while a second block connected to the power supply as the anode is in contact with the piece of work and holds it correctly positioned. Electrons then pass from the cathode block to the anode block through the electrolyte and the piece of work. Desired portions of the surface of the piece of work are etched by allowing the electrolyte and the cathode block to come in contact only with these portions.

In prior art devices this method of etching is generally very slow, complicated and, therefore, costly. In these prior art devices the major problem occurs in the quality of the etching. Unless a great deal of care is used marks etched on consecutive pieces of work may vary greatly in texture and in quality, that is fineness of the lines and fidelity of the pattern. Some of the variables which produce differences in the etched marks are for example: different amounts of electrolyte between the anode and the cathode; different amounts of current or voltage between the anode and the cathode; differences in spacing between the anode and the cathode when the electrical current is passing therebetween; and different amounts of time in which the current passes from the anode to the cathode.

Also, in prior art devices a great amount of work and time is required to change the device in order to produce a different mark. In most cases the die or other device utilized as the pattern is extremely complicated to place in the device and requires special training as well as special tools, etc. The time during which the device is not operating is compounded because the device must be completely de-energized to work on it and, thus, a warm-up time must be allowed after re-energizing the device. In addition, if the device is of the type which utilizes an absorbent material to retain the electrolyte this absorbent material generally becomes dry during the nonoperating time and additional time must be utilized "ice to provide the correct amount of electorlyte in the material.

In the present apparatus a frame with an adjustable platform is provided, which platform has a plurality of adjustments to insure a parallel etching surface between the piece of work andthe die. Also provided on the frame is a motor having a reciprocating arm operatively attached thereto for moving the die precisely into position relative to the piece of work. The motor is connected to the reciprocating arm through a cam-acting member which has a step in the cam surface to insure the speedy removal of the die from the work piece once the correct amount of electric current has passed therethrough. This quick removal of the die [from the piece of work provides a clean circuit break while allowing the electrolyte, to be explained presently, to be quickly exchanged with a fresh supply. Thus, the fidelity and fineness of the lines is increased.

In addition, a ribbon means is utilized, which in this embodiment is an elongated strip of paper having a highly consistent absorbency suflicient to retain an amount of electrolyte that will provide the desired quality of etch ing. Through experimentation it has been found that the absorbency of the paper and, thus, the amount of electrolyte retained greatly effects the fidelity of the marking. In the present invention the reciprocating arm insures a uniform pressure between the die and the work piece on the absorbent paper. Also the absorbent paper is incrementally moved each time the reciprocating arm applies the die thereto, whereby a uniform amount of fresh electrolyte is insured for each marking operation and the reaction products of electrolysis are carried away after the paper is applied to the electrode.

. In addition, in the present invention the die is attached to the reciprocating arm by magnetic means and no other mechanical connection is utilized. Thus, to change the die the operator simply removes the old one and sets a new one in position. This operation can easily be accomplished in a matter of seconds without the use of tools, etc., thereby, greatly reducing or eliminating the shutdown time of the device and simplifying the operation of the machine.

It is an object of the present invention to provide an improved electrolytic etching apparatus.

It is a further object of the present invention to provide an electrolytic etching apparatus having greater consistency and higher fidelity in the marking.

It is a further object of the present invention to provide an electrolytic etching apparatus which is simpler to operate and less expensive to maintain.

These and other objects of this invention will become apparent to those skilled in the art upon consideration of the accompanying specification, claims, and drawings.

Referring to the drawings, wherein like characters indi cate like parts throughout the figures:

FIG. 1 is a view in perspective of the present apparatus;

FIG. 2 is an enlarged view in side elevation of the present apparatus, parts thereof broken away;

FIG. 3 is an enlarged sectional view as seen from the line 33 in FIG. 1;

FIG. 4 is a view similar to FIG. 3, with parts thereof removed, illustrating a different position of the mechanism;

FIG. 5 is a sectional view as seen from the line 55 in FIG. 3; and

FIG. 6 is a sectional view as seen from the line 66 in FIG. 2.

In the figures the numeral 10 generally designates an irregular-shaped housing having a supporting frame 11 therein. The particular shape of the housing 10 and the supporting frame 11 is not important and will not be discussed in great detail in this specification. In FIG. 1 the numeral 12 indicates a control panel and a power supply which is a substantially conventional supply that does not form a part of this invention except to provide current for the electrolytic etching process, The voltage output of the power supply 12 is variable from approximately zero to twelve volts by a rheostat or variable transformer which is controlled through a knob 13 on the control panel 12. The voltage is applied to the mechanical apparatus in a manner to be described presently by means of a cable 14 attached to the control panel 12.

A motor fixedly attached to the frame 11 in the upper portion thereof has a gear box 21 attached thereto for connecting the motor 20 to a horizontal shaft 22 in the right ratio. One end of the shaft 22 has a cam 23 fixedly attached thereto. Cam 23 has a cam surface of the type which gradually increases in diameter until it reaches a maximum point at which there is a step 24 back to the starting point or minimum diameter. An elongated arm 25 is pivotally mounted approximately in the center by means of a bolt or the like so that a roller 26 rotatably attached to the right end thereof (as seen in FIGS. 3 and 4) bears against the cam surface of the cam 23. The left end of the arm 25 has a roller 27 rotatably attached thereto which rests on the upper surface of a horizontal bar 28.

Bar 28 has a pair of shafts 29 and 30 fixedly attached to the undersurface thereof and perpendicular thereto by some means such as welding, threads, etc. A pair of bushings 31 and 32 fixedly positioned coaxially in a pair of vertically spaced apart supports 33 and 34 mount the shaft 29 for vertical movement but substantially no horizontal movement. In a like manner a pair of bushings 35 and 36 fixedly mounted coaxially in the supports 33 and 34 mount the shaft 30 for vertical movement but substantially no horizontal movement. A collar 37 is fixedly attached coaxially to the shaft 29 between the upper support 33 and the lower support 34. A compression coil spring 38 is mounted coaxial with shaft 29 between the collar 37 and the lower bushing 32 to provide a bias on the collar 37. Since collar 37 is fixedly attached to shaft 29 the shaft 29 has a bias thereon tending to maintain it in a normal position. Similarly a collar 39 is fixedly attached to the shaft 30 with a compression coil spring 40 coaxially mounted between the collar 39 and the lower bushing 36 to provide a bias on the shaft 30 tending to maintain it in a normal position. In the normal position the shafts 29 and 30 maintain the horizontal bar 28 pressed against the roller 27 so that the arm 25 is rotated clockwise, in FIG. 3, and the roller 26 bears against the cam 23 at its smallest diameter.

The lower end of the shafts 29 and 30 are fixedly attached to a member having a somewhat rectangular shaped cross section with the lower surface 46 being substantially horizontal. The member 45 has a substantially rectangular-shaped hole 47 approximately centrally located therein and extending from the back surface to the front surface thereof. The utility of hole 47 will be discussed in greater detail later. Member 45 also has a pair of magnets 48 imbedded therein so that one pole of each magnet 48 is flush with the lower surface 46 thereof. The magnets 48 are utilized to attach a die member 50 onto the lower surface 46 of the member 45. These magnets 48 may be of the permanent or of the electromagnet type. Thus, as the cam 23 rotates the arm 25 forces downwardly the horizontal bar 28 with the shafts 29 and 30 attached thereto and, consequently, the member 45 with the die 50 attached thereto. As the cam 23 makes a complete rotation the roller 26 slides over the step 24 and the springs 38 and 40 return the entire mechanism to its normal position.

A portion of the housing 10 and frame 11 extends outwardly adjacent the bottom of the machine toward the front thereof to form a base vertically beneath the die 50. A flat plate 56 fixedly attached to the upper surface of the base 55 has a pair of hollow cylindrical members 57 fixedly attached in an upright position to the upper surface thereof with a traveling screw 58 threadedly engaged in each of the cylinders 57 by means of a knurled nut 59 rotatably attached at the upper end of each of the cylinders 57. The upper end of each of the traveling screws 58 is rotatably attached to the undersurface of a flat substantially horizontal plate 60. Thus, by manually rotating the knurled nuts 59 the plate 60 can be moved vertically and the upper surface thereof can be tilted slightly to make it parallel with the lower surface of the die 50.

A work receiving member 61 is fixedly attached to the upper surface of the plate 60 by some means such as bolts or the like, not shown. The upper surface of the work receiving member 61 can have any desirable shape depending upon the type of work to be marked. In FIGS. 3 and 4 a piece of work 62 is illustrated in dotted lines. The knurled nuts 59 and the traveling screws 58 are set so that the piece of work 62 is pressed slightly between the lower surface of the die 50 and the upper surface of the member 61 when the die 50 is in its lower vertical position, or cam 23 presents its greatest diameter to roller 26.

Ribbon means, which in the present embodiment is a roll of absorbent paper 65 having a width substantially equal to the width of the die 50, is rotatably mounted in the lower rear portion of the housing 10. The paper 65 extends over a roller 66 rotatably mounted in a tank 67 containing a desired electrolyte 68. The electrolyte 68 is a chemical which when placed on the surface of the piece of Work 62 and an electric current passed therethrough causes a portion of the material in the piece of work 62 to go into solution thereby etching the surface. The tank 67 contains a sufficient amount of the electrolyte 68 to cover the lower portion of the roller 66 mounted therein. As the paper 65 moves over the roller '66, the roller 66 is rotated thereby wetting the paper 65 with the electrolyte 68. The composition and surface of the roller 66 are such that the paper 65 receives the correct amount of electrolyte 68 and the absorbency of the paper 65 is such that the correct amount of electrolyte 68 is contained therein to give the desired quality to the marking process.

After the roller 66 the paper 65 extends over a second roller 70, through the central aperture 47 in the member 45, over a pair of members or guides 71 attached to the housing 10 slightly in front of the front surface of the member 45, between the die 50 and the piece of work 62 and between the roller and a driven roller 72. The rollers 70 and 72 are mounted so that the paper 65 extends rearwardly over the lower surface of the die 50 and approximately horizontally. The roller 70 is rotatably mounted on a substantially horizontal arm 73 which is pivotally mounted to the frame 11 at the forward end thereof and has a threaded bolt 74 fixedly attached approximately perpendicular thereto at the other end thereof. When the arm 73 is substantially horizontal the bolt 74 passes through a hole in an outwardly extending portion 75 of the frame 11 and a knurled nut 76 rotatably attached thereto is threadedly engaged with the bolt 74. The knurled nut 76 and the bolt 74 in conjunction with the pivotally mounted arm 73 act as a vertical adjustment for the roller 70 and provide an adjustment for the amount of pressure between rollers 70 and 72.

Roller 72 is positioned vertically below roller 70 and is rotatably mounted to the frame 11 by means of a shaft 77. As seen in detail in FIG 6 the shaft 77 extends through a portion of the frame 11 and has a crown ratchet 78 fixedly attached to the outer end thereof for rotation therewith. A matching crown ratchet 79 is mounted on the inner surface of an arm 80 for engagement with the crown ratchet 7-8. The arm 80 is rotata-bly mounted to the frame 11 coaxial with the crown ratchets 78 and 79 ad jacent one end thereof. The crown ratchets 78 and 79 form a one-way clutch through which movement of the arm 80 in a counterclockwise direction (see FIG 2) causes rotation of the roller 72 in a counterclockwise direction while rotation of the arm 80 in a clockwise direction does not produce movement of the roller 72.

The other end of the arm 80 is pivotally attached to one end of a substantially vertical arm 81. The other end of the arm 81 is pivotally attached to one end of a substantially horizontal arm 82. Arm 82 is pivotally attached to a portion of the frame 11 substantially midway between the center and the free end thereof. A roller 83 is attached to the arm 82 at approximately the center for rotation about an axis substantially parallel to the axis of rotation of the arm 82. A cam 84 is mounted on the free end of the shaft 22 for eccentric rotation vertically below the roller 83 and in contact therewith. One end of a tension coil spring 85 is connected to the arm 82 between the roller 83 and the arm 81 and the other end is connected to the frame 11 so that the arm 82 has a clockwise bias thereon, referring to FIG 2. Thus, the spring 85 maintains the roller 83 in contact with the surface of the cam 84.

As the motor 20 rotates the shaft 22 the cam '84 rotates causing the arm 82 to move the arm 81 vertically in a reciprocatory movement which oscillates the arm 80 and drives the roller 72 incrementally in a counterclockwise direction in FIG. 2. Thus, the incremental movements of the roller 72 in conjunction with the roller 70 pull the paper 65 over the lower surface of the die 50 in predetermined increments. Each of the increments through which the paper 65 moves is sufficient to provide a new portion of paper 65 for each time the die 50 is pressed against the piece of work 62. The cam 84 and the cam 23 are positioned relative to each other so that the paper 65 is moving on the lower surface of the die 50 when the die 50 is moving upwardly or in its upper position and the paper 65 is stationary when the die 50 is in contact with the piece of work 62. In this fashion, a consistent amount of electrolyte 68 appears between the die 50 and the piece of work 62 each time the two are pressed together.

The lead 14 of the power supply 12 is connected to the member 45 so that the member 45 and the die 50 act as the cathode or are negative with respect to ground. The member 61 and consequently, the piece of work 62 are electrically connected directly to the frame 11 which is connected to the positive or ground side of the power supply 12 so that the piece of work 62 acts as the anode. Thus, when the die 50 is moved vertically downward and pressed against the piece of work 62 with the paper 65 therebetween electrons flow from the die 50 through the electrolyte 68 in the paper 65 to the piece of work 62. As current flows through the electrolyte 68 and the piece of work 62 part of the material in the surface of the piece of work 62 goes into solution in the electrolyte 68 contained in the paper 65 in contact therewith and an etching or marking occurs. This marking occurs wherever the current flows through the electrolyte 68 and, since the desired pattern is in relief on the die 50, a pattern is etched on the surface of the piece of work 62 similar to the pattern in relief on the die 50.

The present invention provides marks of good fidelity and consistent quality because the amount of electrolyte 68 between the die 50 and the piece of work 62 is always consistent. The pressure and the amount of time which the die 50 is forced against the piece of work 62 is equal for each operation and the upper surface of the piece of work 62 is always parallel to the lower surface of the die 50 which provides equal current through the electrolyte 68 over the entire pattern.

While I have shown and described a specific embodiment of this invention, further modifications and improvements will occur to those skilled in the art. I desire it to be understood, therefore, that this invention is not limited to the particular form shown and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.

I claim:

1. Electroyltic etching apparatus comprising:

(a) a frame having a work receiving adjustable platform thereon;

(b) a motor fixedly attached to said frame;

(c) reciprocatory means mounted on said frame for reciprocatory movements relative to said platform and operatively connected to said motor;

((1) die means being at least partially composed of electrical conducting material and having desired patterns in relief thereon;

(e) magnetic means fixedly attached to said first reciprocatory means for holding said die means in an operating position relative to said platform and providing an electrical circuit between said die means and said reciprocatory means;

(f) ribbon means having means associated therewith for applying an electrolyte thereto movably attached to said frame and having a portion thereof between said die means and said platform;

(g) means operatively attaching said ribbon to said motor for incrementally moving said ribbon means to periodically change the portion of said ribbon 'between said die means and said platform; and

(h) a power supply attached to said platform and said reciprocatory means for providing an electric etching current therebetween during periods of contact between said platform, a piece of work, said ribbon means and said die means simultaneously.

2. Electrolytic etc-hing apparatus comprising:

(a) a frame having a work receiving adjustable platform thereon;

(b) a motor fixedly attached to said frame;

(c) reciprocatory means mounted on said frame for movements to a first position in juxtaposition to said platform and to a second position substantially spaced therefrom, said reciprocatory means being operatively connected to said motor;

(d) die :means being at least partially composed of electrical conducting material and having desired patterns in relief thereon;

(e) magnetic means fixedly attached to said reciprocatory means for holding said die means in a position interposed between said reciprocatory means and said platform, said magnetic means providing an electric circuit between said die means and said reciprocatory means;

(-f) ribbon means having means associated therewith for applying an electrolyte thereto movably attached to said frame and having a portion thereof between said die means and said platform;

(g) means operatively attaching said ribbon to said motor for incrementally moving said ribbon means to change the portion of said ribbon between said die means and said platform when said reciprocatory means is approximately in its second position; and

(h) a power supply attached to said platform and said reciprocatory means for providing an electric current therebetween during periods when a piece of work is correctly positioned on said plat-form and said reciprocatory \means is in said first position.

3. The electrolytic etching apparatus of claim 2 wherein the reciprocatory means includes a cam acting member having a step in the cam surface to provide substantially faster movement of said reciprocatory means from the first position to the second position than from the second position to the first position.

4. The electrolytic etching apparatus of claim 2 wherein the work receiving adjustable platform has a plurality of adjustments for providing parallel surfaces between the work piece and the die means.

5. The electrolytic etching apparatus of claim 2 Wherein the ribbon means comprises an elongated strip of absorbent paper capable of retaining an amount of electrolyte sufiicient to provide the desired quality of etching.

References Cited UNITED STATES PATENTS Bartholomew et al. 204-143 XR HOWARD S. WILLIAMS, Primary Examiner. 10 D. R. VALENTINE, Assistant Examiner. 

1. ELECTROYLTIC ETCHING APPARATUS COMPRISING: (A) A FRAME HAVING A WORK RECEIVING ADJUSTABLE PLATFORM THEREON; (B) A MOTOR FIXEDLY ATTACHED TO SAID FRAME; (C) RECIPROCATORY MEANS MOUNTED ON SAID FRAME FOR RECIPROCATORY MOVEMENTS RELATIVE TO SAID PLATFORM AND OPERATIVELY CONNECTED TO SAID MOTOR; (D) DIE MEANS BEING AT LEAST PARTIALLY COMPOSED OF ELECTRICAL CONDUCTING MATERIAL AND HAVINF DESIRED PATTERNS IN RELIEF THRERON; (E) MAGNETIC MEANS FIXEDLY ATTACHED TO SAID FIRST RECIPROCATORY MEANS FOR HOLDING SAID DIE MEANS IN AN OPERATING POSITION RELATIVE TO SAID PLATFORM AND PROVIDING AN ELECTRICAL CIRCUIT BETWEEN SAID DIE MEANS AND SAID RECIPROCATORY MEANS; (F) RIBBON MEANS HAVING MEANS ASSOCIATED THEREWITH FOR APPLYING AN ELECTROLYTE THERETO MOVABLEY ATTACHED TO SAID FRAME AND HAVING A PORTION THEREOF BETWEEN SAID DIE MEANS AND SAID PLATFORM; (G) MEANS OPERATIVELY ATTACHING SAID RIBBON TO SAID MOTOR FOR INCREMENTALLY MOVING SAID RIBBON MEANS TO PERIODICALLY CHANGE THE PORTION OF SAID RIBBON BETWEEN SAID DIE MEANS AND SAID PLATFORM; AND (H) A POWER SUPPLY ATTACHED TO SAID PLATFORN AND SAID RECIPROCATORY MEANS FOR PROVIDING AN ELECTRIC ETHCING CURRENT THEREBETWEEN DURING PERIODS OF CONTACT BETWEEN SAID PLATFORM, A PIECE OF WORK, SAID RIBBON MEANS AND SAID DIE MEANS SIMULTNEOUSLY. 